The present invention relates to a support with at least one wearing part, particularly a wear shoe, for screw presses with a screw flight, where the support can be secured to the screw flight, where the wearing part is connected to the support by a positive and a substance-to-substance bond, and where the wearing part and the support are connected to one another by a positive bond in which a projection in one of the two parts meshes into a recess in the other part.
Furthermore, the invention relates to a screw press for removing liquid from a pulp suspension, which has a shell, having openings through which the liquid passes, and a screw with screw flight, to which supports with wearing parts are secured, rotating inside the shell.
For removal of liquids from pulp suspensions by means of screw presses the use of so-called wear shoes at the outer radial edges of the screw flight is itself known from the state of the art. Since screw presses have a high-pressure section, the operating conditions of the wear shoes are characterised by very strong forces acting on the wear shoes. As a result, the wear shoes must be connected to the screw flight with high precision. This connection was formed so far by welding, which led to undesirable stresses occurring.
DE 19820044C2 describes a wear shoe that is made of a similar or the same material as the screw flight in order to prevent uncontrollable material damage during welding as a result of different materials being used. Practical operation has demonstrated, however, that securing of wear shoes to the screw flight can be improved.
In addition, wearing parts for centrifuges are known, e.g. from WO 81/02853 and WO 95/24352. Here, in particular, the centrifugal forces must be taken into consideration, whereas in screw presses the pressing forces on the face end and the forces generated by friction in circumferential direction must be taken into account. Thus, the solution for centrifuges cannot be applied to screw presses.
DE 32 49 999 C1 shows a conventional screw press with wearing elements on a screw shaft. The screw flight is interrupted here and at this point, doctor-like screw flight tips are mounted, which have a wearing layer and a connected to one another either by a bolt or by welding. DE 42 12 217 A1 describes a device for attaching wearing elements to screw flights using adhesive.